Filter



Deb. 6, 1932. 5. J. FOWLER; v 1,890,251

7 FILTER Original Filed Aug. 29. 1927 2 Sheets-Sheet. l

G- J. FOWLER Dec. 6, 1932.

FILTER 1927 2 Sheets-Sheet 2 Original Filed u 29 Patented Dec. 6, 1932 UNITED STATES.

GILBERT J. FOWLER, OF GALORE, INDIA FILTER Application filed August 29, 1927, Serial No. 216,117. Renewed May 21, 1932.

This invention pertains to a method or process of filtering and drying and to means for carrying out this process, and relates more particularly to the treatment of the fiocculent sludge obtained in disposing of sewage. By the activated sludge treatment, large quantities of sewage, consisting of about 97% water, 1% inorganic matter and 2% organic matter, such as carbohydrates,

fats, albuminous matter, urea, etc., are mixed with a smaller quantity of sludge which has been activated by a prior treatment, and this mixture is subjected to a treatment with air bubbles whereby thebacteria cause the nitrification or oxidation of the organic solids to yield forms of ammonia, nitrates, acids, etc.,

thus converting a large proportion of the sewage into soluble compounds and causing the remaining portion to coagulate into a floceulent sludge.

The solid matter resulting from this treatment contains matter which is very valuable as a fertilizer, the activated sludge treatment rendering the solids even more valuable because atmospheric nitrogen is actually absorbed from the air and stored by the organisms in the above treatment. From the point of view of the value of the manure of fertilizer, it is vital that it should not be overheated or treated with chemicals; e. g., with acid, it this can be avoided. Overheating tends to render the nitrogen less available and the addition of acid cannot be of benefit to the product.

The nature of the. solids, however renders them extremely difficult to liter. The finelydivided matter, which is in the defloeeulated form, will tend to pass through an ordinary.

filter and clog its pores. Screens and sand filters have been usually used for this purpose but the action is very slow, the filter becomes clogged, the separation is not thorough, and

Another object is to provide an improved filtering system and means for removing the residue therefrom.

Another object is to separate well-conditioned sludge from sludge of indifferent quality so that the latter may be returned for further treatment. i 7

Another object is to provide a method and means for dryingthe residue on the filter by means of air currents.

Another object is to provide a continuous process wherein the filter is conditioned prior to its use by passing it through a mois- I ture chamber.

Another object is. to provide improved means for removing the filtrate from a filter of this nature.

Another object is to. reduce the cost of filtering and drying so that the fertilizer may be commercially profitable. r

Another object is .to provide improved apparatus for carrying out my process.

Other objects will appear as the detailed description of my invention proceeds.

In the accompanying drawings whichillustrate a preferred embodiment of myinven 7 tion and in which similar reference character relate to similar parts throughout,

Fig. l is a perspective view showing the driving means, thesupports, the casing, etc.

Fig. 2 is a vertical section of the casing shown in Fig. 1, showing the arrangement of the filter mat. i

Fig. 3 is an enlarged detail showing the general structure of the filter mat.

Fig. 4 is a detail of the mat support, its roller, roller support, and corrugateddrain.

Fig. 5 is a detail showing theconstruction of the pulley, over, which the filter belt is trained. n

Fig. 6 is a detail showinganother modification of a belt si'ipporting roller.

Figs. 7 and 8 are horizontal and vertical details of still another modification of a belt support.

The present application relates particularly to thefilter per se, and the complete apparatus and method of filtering and drying have been made the subjects of two divsioual applications, executed March 31. 1932, Ap-

paratus for separating solids from liquids,

and Processes for separating solids from liq uids, respectively.

Referring to Figs. 1 and 2, a suitable casing 11 encloses a brush mat, filter 12 in the form of a'belt which is driven by pulleys 13 and 14 in a counter-clockwise direction, as shown in Fig. 2. The casing may be of wood, metal or any other suitable structure and in some cases may be omitted entirely, its function being tozmaintain the warm air in contact with the sludge on the filter. The casing is provided with a suitable support 15 on which may be mounted'a motor 16 equipped with a driving belt or chain 17 for synchronously driving pulleys18 and 19, secured to shafts 20 and Y21, respectively, on

' the outside of the casing.

' By providing a pos tive drive for these shafts, pulleys 13 and 14, which'are also keyed to shafts 20 and 21, respectively, are positively driven at'the same speed, so that there will be no tendency to stretch the mat and increase the'distance between the supporting bars, as will be further explained.

\Keyed to shaft 20 on the outside of the casing (Fig. 1) is a pulley 22, over which a crossed belt 23 is trained to drive pulley 24,

' keyed to shaft 25, to which is also keyed a roller 26, the function of which will be set forth below.

The lower part of the lower'end of the casing is provided with an outlet 27 and the upper part of this end is provided with an inlet 28 for a drying gas, such as heated air. The

. motor for driving the pulleys may be also used to operate a compressor for forcing air into the chamber through opening 28. Also, a suitable heater may be installed for warming the drying gas. The compressor and heating means (not shown in the drawings) may be of any conventional type.

' At the other end of the casing 11 there is provided an inlet penstock 29, including a chute 30 and a sluice-gateSl, which is adapt ed to be adjusted to vary the amount of sludge delivered to the filter mat. The upper end of the chute is provided with a hopper 32, adapted to receive sludge from the sludge delivery pipe 33. Around hopper '32 and extending above its uppermost limit is an overflow funnel 84, adapted to carry away any of the sludge running over the top of hopper 32. A pipe carries the overflow" sludge back to itsoriginal source, from whence it is pumped againto the chute. By

this'means, a constant head and a continuous and evenly-distributed flow of the sludge on the filter mat is obtained.

The casing 11 surrounding the filter belt is divided into two compartments. a moi ture chamber 36 and a drying chamber 37. Pulleys are mounted on these two chambers. as heretofore expla ned, and a fiber mat filter belt is trained ver these pulleys so that it receives the slu ge in the moisture chamber,

v The brush cycle.

innumerable, vertical fibers. A detail of allows the water to drain ofl' therein, carries the residue on the filter through the drying Y chamber. deposits'the dried residueat the lower end of the chamber, and returns through the moisture chamber to repeatthe mat filter is preferably of coir, 1 such as is used forhigh-class door mats, thew) surface of which is composed of the ends" of l j the mat 12 is shown in Fig. 3, wherein the base portion 38 is shown as a woven mat supporting innumerable, vertical fibers 39. The

material of which the matandvertical fibers I are composed may be co1r, cocoanut fiber, 3

hemp, vegetable fiber, hair, metal wires, etc.,

it being only necessary that the filter be unaffected by the substance to' be filtered. In

any event, the innumerable, vertical fibers constitute virtually azstream-line filter c'omposed of a countless number-of vertical channels, whereby the draining effect is enormous ly intensified.

An important feature of a filter of this type is the fact that-it does-not'become clogged by the deflocculated or colloidal matter carried by the liquid. Particles-whicharetoo small to be retained by thefilter pass'thr'ough it with the fluid. This feature is especially advan-. tageous in the treatment of activated sludge because it retains all-of the properly conditioned sludge andallow's the portion of sludge which hasnot been sutficiently aerated to bereturned for re-treatment. This avoids the necessity of treating the whole :batch for an extended period of time to thoroughly com-' plete'the reaction; that is, where it hasheretofore been necessary to aerate the-sludge for an extended period, it will now require aniuch less period because any of the sludge which:

' has escaped treatment may be easily filtered and re-treated.

Another important feature of this filter is v as that of the belt. This acts to thoroughly A sweep the opened fibers and remove all of the residue therefrom. By this treatment there are no pores to become clogged and there is i 'no tendency to drive the substance to be removed into the pores of the filter asis the case with ordinary filter cloths. By my im-' proved process, I am able to use the same filter continuously "for an extended period of time without decrease infilter efficiency, even when thte material is a gelatinous mud or precipita e.

It has been foundthat with'certain types of brush matfilters, such as the typeused for- 7 be damp if the sludge is to spread evenly over I the surface and to be properly filtered. To accomplish this purpose I have arranged my 10 apparatus whereby the filter mat 12 is passed through a portion of the moisture chamber'36 on its return to the inlet chute, whereby the filter is re-conditioned (moistened) and prepared to receive-another batch of the sludge.

The'means for carrying. away the filtrate in chamber 36 is preferably'a sheet of corrugated, galvanized iron 40in which the channelsor corrugations are slightly inclined longitudinally to allow thewater to readily flow into trough 41, whence it is conducted by pipe 42 (Fig. 1) to a re-treatment tank not shown. Since moisture may condense in chamber 36, I have provided another trough 43, connected by pipe 44 to pipe 42,'whereby '25 this moisture is also removed and prevented from flowing down the casing to come in tact with the dried residue.

The moisture chamber 36 is separated from the drying chamber 37 by a plate 45, which 80 plate must necessarily have openings at 46 and 47 through which the. belt may pass. I The lower part of the casing which comprises drying chamber 37 is provided with an inlet 28 for heated air. A bafile-plate 48 prevents the heated air from escaping through the outlet 27 and directs it along the upper surface of the belt. The counterourrent principle is applied; that is, the dry air comes in contact with the material nearest pulley 13, and as the air becomes'more saturated, it comes in contact with residue which contains more moisture. The structure of the fiber mat filter holds the residue in suspension to allow air to circulate freely above and below it-whereby drying is accomplished most rapidly.

An exit port 49 is provided in the casing at the upper end of the drying chamber 37 so that these gases may be carried, together 60 with their moisture, from the system. This port also serves as an exit for moisture intro duced into chamber 37 by air circulating through chamber 36.

Various means may be used for supporting the mat. In Figs. 2, 4 and 5, I have shown steel bars 50, spaced at intervals throughout the length of the belt, and secured thereto in any suitable manner. These bars are provided at each end with suitable rollers 51, rotatably mounted thereon, and held in place by suitable washers 52 and locknuts 53.

These rollers are adapted to travel in and be supported by channels 54 which are inclined at 55 to form an approach for the rollers.

The supporting rollers 51 maybe flanged.

as shown inFig. 6, and adapted to travel on rails 56 instead of channels. Instead of rollers,"slidin contacts 57 may be used to coact with a suitable slide 58, as shown in Figs. 7 and 8.

"The pulleys 13 and 14 comprise two discs 59 held in fixed positionrelativc to each other by spacing bars 59a rigidly secured thereto.

Spaced lugs 60 are carried by these pulleys and are adapted to catch the support-in rods 50 between the rollers 51 and the brusli mat Should the belt be- 12, as shown in Fig.

come stretched for any reason, the distance between rods 50 would be increased and would not accurately register with the distance between lugs 6O on discs 59. To prevent this, I may mount the filter mat on suitable metallic mesh, or I may provide means for holding the bars 50 equally spaced from each other. This means per se does not constitute a part of my invention and needs no further description. I v

While I have described a preferred embodiment of my invention, it is understood that various other embodiments might suggest themselves to anyone skilled in the art. For instance, instead ofarranging the filter as an endless belt on pulleys, the filter mats may be arranged in vertical layers, with corrugated iron sheets therebetween and a drying gas may be introduced at intervals.

If the atmospheric conditions and the cliing but may consist of loosely piled rocks or any other conventional means for rapidly carrying away the water.

The essence of the invention is the use of an improved filter and drying means, and while I have described in detail an application .of this to activated sludge, it is understood that the invention applies equally to all processes wherein a solid of this nature must be removed from a liquid. My invention applies especially wherever filter cloths have been used heretofore, in centrifugal machines, etc.

The expression brush mat, as used in this specification and in the following claims, is not limited to vegetableiibers' or bristles but includes any type or means wherein the supporting surface is composed of the ends of innumerable upstanding fibers, the fibers consisting of coir, wood, reeds, grass,hair, metal wires, etc.

What I claim and desire to secure by Let- 1 ters Patent of the United States is:

1. A filter comprising a supporting base providedwith a multiplicity of projecting. bristles located sufliciently close to eac other to form asupporting surface for the major portion of the solid material to be separated by said filter, said filter base com: prising a flexible belt adapted to be bent about a curved surface to spread said bristles and facilitate cleaning of said filter.

2. A filter comprising an endless supporting base provided with a multiplicity of projecting bristles located sufficiently close to each other to form a supporting surface for the major portion of the solid material to be separated by said filter, said supporting base comprising a woven mat.

3. A filter comprising a woven mat formed of fibers of coir having a multiplicity of outwardly projecting bristles, the bristles being located sufliciently close together to form a supporting surface located at the ends of the bristles for supporting the major portion gf the solid material' to be separated by said lter.

4. A filter comprising a woven mat formed of fibers of coir having a multiplicity of outwardly projecting bristles, the bristles being located sufliciently close together to form a supporting surface located at the ends of the bristles for supporting the major portion of the solid material to be separated by said filter, and the bristles extending substantially in the direction of flow of the fluid through said filter, thereby facilitating the streamline flow along the bristles and resulting in quick separation of the solid material.

5. A filter for separating sludge from liquid, comprising a woven mat having a flexible base and a multiplicity of outwardly projecting bristles, said bristles being sufficiently stiff, numerous and located close together to form a supporting surface at the ends of the bristles for the residue, and said bristles extending substantially in the direction of flow of the liquid from said sludge,

.thereby facilitating quick drainage of the residue;

6. A supporting member for drying a residue, comprising a mat having a multiplicity of outwardly projecting bristles, said bristles being sufficiently stiff, numerous and located close together to provide a supporting surface at the ends of the bristles for the residue, and the bristles permitting the circulation of air between the bristles underneath the residue as well as on the other side of the residue to facilitate quick drying.

In witness whereof, I hereunto subscribe my name this 20th day of July, 1927.

GILBERT J. FOWVLER. 

